Exploring the Optimal Concentration of Lidocaine Test Dose for Labor Analgesia

This study aims to compare the analgesia effects and side effects of different concentrations of test dose lidocaine (1.5% lidocaine 3 ml, 1.0% lidocaine 5 ml, 0.5% lidocaine 10 ml) in labor analgesia, so as to provide a scientific basis for the clinic al practice of labor analgesia.

Study Overview

• Status: Active, not recruiting
• Conditions: Labor Pain
• Intervention / Treatment: Drug: 1.5% Lidocaine; Drug: 1.0% Lidocaine; Drug: 0.5% Lidocaine

Detailed Description

Epidural analgesia is the most effective and widely used analgesic method for relieving labor pain in clinical practice. However, inadvertent insertion of an epidural catheter into a blood vessel or subarachnoid space may result in local anesthesia or total spinal anesthesia, which can be life-threatening. Therefore, a low-concentration, low-volume dose of local anesthetic is usually injected as a test dose before injecting a large dose of local anesthetic through the epidural catheter to ensure that the catheter is within the epidural space. At present, the guidelines recommend 3 ml of 1.5% lidocaine as the test dose, but in clinical practice and the study of Chen et al., it was found that the test dose of 1.5% lidocaine 3ml still has a high incidence of lower limb motor block of 57.1%, which affects maternal activity and labor progression. In addition, Liu Henry et al. found that the incidence of 0.5% lidocaine 10 ml test dose-induced motor block was 0%, and the analgesic effect could be quickly achieved. Therefore, it is uncertain which concentration of lidocaine has the fastest onset of analgesia and the fewest side effects in labor analgesia. Therefore, this study aims to compare the effects of different concentrations of lidocaine (1.5% lidocaine 3 ml, 1.0% lidocaine 5 ml, 0.5% lidocaine 10 ml) in labor analgesia, so as to provide a scientific basis for the clinical practice of labor analgesia.

• Study Type: Interventional
• Enrollment (Estimated): 99
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Chongqing
    • Chongqing, Chongqing, China, 400000
      • The Second Affiliated Hospital of Chongqing Medical University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Singleton primipara
2. Aged 20-40 years
3. Pre-assessed as eligible for vaginal delivery
4. Height between 155-170 cm, BMI between 18.5-35 kg/m²
5. Cervical dilation between 2-6 cm
6. No significant history of cardiopulmonary disease
7. No history of surgical trauma
8. American Society of Anesthesiologists (ASA) Grades I-III
9. Patients are willing to participate and be able to understand and sign an informed consent form

Exclusion Criteria:

1. Contraindications for spinal anesthesia, such as coagulopathy or ongoing anticoagulant therapy, infection at the puncture site, bacteremia, epidural abscess, increased intracranial pressure, severe hypovolemia
2. Physical or mental disabilities, such as scoliosis and depression, alcohol or drug abuse
3. Major organ diseases, such as hyperthyroidism, cardiopulmonary diseases, diabetes treated with insulin, and neuromuscular diseases
4. Numerical Pain Rating Scale (NPRS) < 5
5. Refusal to participate in the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 1.5% Lidocaine; After successful epidural puncture, 3ml of 1.5% lidocaine was injected as a test dose	Drug: 1.5% Lidocaine; After successful epidural puncture, 3ml of 1.5% lidocaine was injected as a test dose; Other Names: Lidocaine
Experimental: 1.0% Lidocaine; After successful epidural puncture, 5ml of 1% lidocaine was injected as a test dose	Drug: 1.0% Lidocaine; After successful epidural puncture, 5ml of 1% lidocaine was injected as a test dose
Experimental: 0.5% Lidocaine; After successful epidural puncture, 10ml of 0.5% lidocaine was injected as a test dose	Drug: 0.5% Lidocaine; After successful epidural puncture, 10ml of 0.5% lidocaine was injected as a test dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The incidence of motor block	Bromage Scores were used to grade movement block: I free movement of legs and feet, II free movement of feet with only bent knees, III free movement of feet without bending knees, IV no movement of legs and feet, with scores of II, III and IV considered as movement block.	3,5,7,9,11,13,15,20,25,30 minutes after lidocaine administration

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain scores	Pain scores is assessed by the Numerical Pain Rating Scale (NPRS, where 0 means no pain and 10 means no pain tolerance)	3,5,7,9,11,13,15,20,25,30 minutes after lidocaine administration
Time of analgesia onset	Pain scores is assessed by the Numerical Pain Rating Scale (NPRS, where 0 means no pain and 10 means no pain tolerance). Analgesia is considered effective when NPRS is ≤3 or NPRS is reduced by ≥ 50% of the baseline value.	3,5,7,9,11,13,15,20,25,30 minutes after lidocaine administration
Sensory block level	Midabdominal line acupuncture was used to assess the sensory block level	3,5,7,9,11,13,15,20,25,30 minutes after lidocaine administration
Incidence of complications related to labor analgesia	Ask the patient if they have discomfort such as leg warmth, leg numbness, trembling, itching, headache, tinnitus, etc.	30 minutes after lidocaine administration
frequency and intensity of uterine contractions	A contraction monitor is used to monitor the intensity and frequency of contractions	30 minutes after lidocaine administration
Maternal blood pressure	Automated monitoring with an ECG monitor	5,10,15,20,25,30 minutes after lidocaine administration
Maternal heart rate	Automated monitoring with an ECG monitor	5,10,15,20,25,30 minutes after lidocaine administration
Pulse oximetry （SPO2）	Automated monitoring with an ECG monitor	5,10,15,20,25,30 minutes after lidocaine administration
fetal heart rate	Automatically monitored using a fetal heart rate monitor	5,10,15,20,25,30 minutes after lidocaine administration
Patient satisfaction score	Numerical rating scale was used to score (0, completely dissatisfied; 1. Neutral; 2, satisfaction; 3, completely satisfied)	30 minutes after lidocaine administration
First stage of labor	The first stage of labor begins when labor starts and ends with full cervical dilation to 10 centimeters.	From enrollment to 1 minute after the baby comes out.
Second stage of labor	The time from the cervix dilated to 10 centimeters to the baby comes out.	From enrollment to 1 minute after the baby comes out.
neonatal Apgar score	The Apgar score is to evaluate the presence or absence of neonatal asphyxia and the severity of asphyxia from five aspects: Appearance, Pulse, Grimace, Activity and Respiration after birth, with each item being 0~2 points and a full score of 10 points.	1, 5, and 10 minutes after baby comes out.

Collaborators and Investigators

• Sponsor: The Second Affiliated Hospital of Chongqing Medical University
• Investigators: Principal Investigator: Bing Chen, The Second Affiliated Hospital of Chongqing Medical University

Study record dates

Study Major Dates

• Study Start (Actual): March 10, 2025
• Primary Completion (Estimated): October 30, 2026
• Study Completion (Estimated): December 30, 2026

Study Registration Dates

• First Submitted: January 24, 2025
• First Submitted That Met QC Criteria: February 8, 2025
• First Posted (Actual): February 11, 2025

Study Record Updates

• Last Update Posted (Actual): June 2, 2025
• Last Update Submitted That Met QC Criteria: May 28, 2025
• Last Verified: February 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Labor Pain; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Peripheral Nervous System Agents; Anesthetics, Local; Anesthetics; Central Nervous System Depressants; Sensory System Agents; Anti-Arrhythmia Agents; Voltage-Gated Sodium Channel Blockers; Sodium Channel Blockers; Membrane Transport Modulators; Lidocaine
• Other Study ID Numbers: 2024.276

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual participant data (IPD) will be available with the responding author when required.
• IPD Sharing Time Frame: The data will become available when publish and keep it for 5 years.
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound proposal.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No